Stats in R: Class Test 2 Flashcards
What does a Chi-Squared do?
Provides an analysis of frequency data between observed and expected data
How do you know if the Chi-Squared shows a significant difference?
If the critical value is less than the computed value
What does a t-test analyse?
Variance
What does a t-test compare specifically?
Means and variances of two or more datasets
When is a t-test suitable?
When data is normally distributed or sample size is large
What do one-sample and two=sample t-tests against?
A one-sample t-test, tests against a regulatory limit or identified value and a two-sample for one mean against the other
ANOVA analysis should be used on what kind of data?
Categorical
What test can be used if the sample is non-normally distributed?
The Two sample Mann-Whitney U Test
How should the Residual and QQ Plot look for ANOVA model checking?
Residuals should have no obvious structure between stack and QQ plot should have all points on the 45 degree line or close
When is ANOVA appropriate?
When comparing means and variances of two or more datasets and if the dataset includes replication (variation)
When should a transform be used?
When data is non-normal and positively skewed and model checking is not successful
How is a maximal model created?
Include all EVs as well as any interaction between them with *
How is the Minimum Sufficient Model reached?
Remove the least significant variable, one by one until all variables are significant
What does the Tukey “Honest Significant Difference” function identify?
Determines between which groups that there is a significant difference
